发出DbContext.OnModelCreating每个上下文创建 [英] Emit DbContext.OnModelCreating on every context creation
问题描述
我使用实体框架代码先用我的数据库工作。
我有不同的名称,但相同的结构几个表,这表动态出现在数据库中。我怎么会在运行时和使用数据映射的EntityFramework到表中的一个,就像我工作过这样的的DbContext实体?
I use entity framework code first to work with my database. I have several tables with different names but same structure, and this tables dynamically appears in database. How could I map EntityFramework to one of that tables at run-time and use data from just like I work this over entities of DbContext?
我所做的使它的工作:
例如,我的课有什么介绍了动态创建的表的结构是 SetElement
For example, my class what describes structure of dynamically created table is SetElement
.
下面是我的背景:
public class DataContext : DbContext
{
public DataContext()
: base("RepositoryConnectionString") { }
string setElementsTableId; // the name of table that need to be dynamicly mapped to
// Enforce model recreating
public DataContext(string setElementsTableId)
: this()
{
this.setElementsTableId = setElementsTableId;
}
/* some other entities */
public DbSet<Entities.SetElement> SetElements { get; set; } // dynamicly mapped entity
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
/* come configurations */
if (!string.IsNullOrEmpty(setElementsTableId))
{
modelBuilder.Entity<Entities.SetElement>().Map(x => x.ToTable(setElementsTableId)); // map SetElements property to dynamicly created table
}
}
}
我如何使用这样的:
public static void AddSetElements(ICollection<SetElement> setElements, string tableId)
{
using (ctx = new DataContext(tableId)) // configere DataContext to map tableId table for entity SetElements
try
{
var num = ctx.SetElements.Count();
ctx.SetElements.AddRange(setElements);
ctx.SaveChanges();
}
catch (Exception e)
{
}
}
我也有一些方法来获得,udtate并从动态地创建的表是一样的,以 AddSetElements
数据。
I have also some methods to get, udtate and remove data from dynamicly created tables that are same to AddSetElements
.
所有作品一样祝但只有当 AddSetElements
先运行,因为在第一次的datacontext创建 DbContext.OnModelCreating
运行,并配置所有映射。但接下来的实例创建不叫 DbContext.OnModelCreating
All works just as I wish but only if AddSetElements
runs first, because at the first datacontext creating DbContext.OnModelCreating
runs and configure all mappings. But next instance creation doesn't call DbContext.OnModelCreating
.
所以,我的问题是:如何调用 DbContext.OnModelCreating
创建的DataContext
然后使用的DataContext(字符串setElementsTableId)
来创建它?
So, my question is: how to call DbContext.OnModelCreating
everytime of creating an instance of DataContext
then I use DataContext(string setElementsTableId)
to create it?
我知道,我的问题是在EF动态映射表类似,但是我发现没有什么结果。
I know, my question is similar to 'dynamic table mapping in EF' but I found nothing in the results.
顺便说一句。如果你知道另一种方式来解决我的问题,欢迎您。
By the way. If you know another way to solve my problem, you are welcome.
推荐答案
有一个内置的功能,可满足您问题:`IDbModelCacheKey;它的实施是在配置中进行登记。
关键是要为您的不同的地方不同的密钥
There is a built-in feature which may address your issue : `IDbModelCacheKey ; the implementation of which is to be registered in your configuration. The point is to generate a different key for your different contexts.
我会去是这样的:
首先,配置
public class EntityFrameworkConfiguration: DbConfiguration
{
public EntityFrameworkConfiguration()
{
this.SetModelCacheKey(ctx => new EntityModelCacheKey((ctx.GetType().FullName + ctx.Database.Connection.ConnectionString).GetHashCode()));
}
}
然后IDbModelCacheKey实施
Then the implementation of the IDbModelCacheKey
public class EntityModelCacheKey : IDbModelCacheKey
{
private readonly int _hashCode;
public EntityModelCacheKey(int hashCode)
{
_hashCode = hashCode;
}
public override bool Equals(object other)
{
if (other == null) return false;
return other.GetHashCode() == _hashCode;
}
public override int GetHashCode()
{
return _hashCode;
}
}
最后,你的DataContext
Finally, your DataContext
public class DataContext : DbContext
{
string setElementsTableId;
// use the setElementsTableId as extended property of the
// connection string to generate a custom key
public DataContext(string setElementsTableId)
: base(ConfigurationManager.ConnectionStrings["RepositoryConnectionString"]
+ "; Extended Properties=\"setElementsTableId=" + setElementsTableId + "\"")
{
this.setElementsTableId = setElementsTableId;
}
public DbSet<Entities.SetElement> SetElements { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
if (!string.IsNullOrEmpty(setElementsTableId))
{
modelBuilder.Entity<Entities.SetElement>().Map(x => x.ToTable(setElementsTableId));
}
}
}
我希望这将是一些帮助
I hope this will be of some help
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